Textscan vs importdata
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Hi,
I though textscan was faster than importdata but it seems to me that for bigger file importdata is faster. Any explanations?
Here is the code :
tic
raw1=importdata('185mo.csv');
toc
tic
fid = fopen('185mo.csv');
raw2 = textscan(fid, '%f %f %f', 'delimiter', ',', ...
'EmptyValue', -NaN,'HeaderLines',16);
fclose(fid);
toc
Here is the result :
Elapsed time is 30.462402 seconds.
Elapsed time is 38.665811 seconds.
4 个评论
Oleg Komarov
2012-2-14
Consider that importdata uses textscan. I would suggest to go in debug mode to check what options they use, but I suspect it's the NaN padding.
Walter Roberson
2012-2-14
Interesting, I did not know that -NaN had a different representation than NaN, but it seems to (in R2008b at least)
>> sprintf('%16lx\n',typecast(nan,'uint64'))
ans =
fff8000000000000
>> sprintf('%16lx\n',typecast(-nan,'uint64'))
ans =
7ff8000000000000
Benoit
2012-2-14
回答（1 个）
xiangsheng guan
2012-7-9
0 个投票
I find that importdata uses fread for .txt files. But I can access neither source file of fread nor textscan.
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2013-10-12
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